My muscle memory is still adjusting to Apple's late April Fools scrolling joke, but already I am appreciating the little bits of Lion, especially full screen mode. As many have already pointed out, it doesn't really make much sense on a big screen, but on a laptop, especially the 11" MacBook Air, it's magic, especially combined with the "next desktop" gesture. I did some Rails coding on the couch yesterday. I had Terminal and Safari both full-screen, and swiped my way back and forth. My wife, who as a matter of principle shows no interest in OS upgrades, oohed and aahed at this. (She still misses the Windows "maximize" feature, and this is the closest Apple has come to date).
Speaking of Terminal, when you create a new tab it defaults to the directory you were on in the previous tab, which is all I've ever really asked for.
Everything just seems a little smarter. Many of the sharp edges of my electronic life (some of which I didn't even know I had) have been buffed smooth. Some folks hate all the animation, and maybe I'll get sick of it eventually. But life is full of abrupt transitions, and I very much appreciate Apple's efforts to make theirs as pleasant as possible.